Method and apparatus for cutting steel to reduce slag adherence

ABSTRACT

A steel cutting apparatus includes a cutting torch that is moved in an arcuate path for guiding the cutting torch so that a cutting flame of the cutting torch is always aimed at a bottom corner of the steel at the side where the cutting process begins. Molten steel and iron oxide flow through a kerf in the steel toward the bottom corner, and drop away from the billet for collection and disposal. Only a very small amount of slag adheres to the bottom corner of the billet when cutting is complete.

FIELD OF THE INVENTION

[0001] The present invention relates to a process for separation ofmetallurgical products, such as steel billets, blooms or small slabs,and more particularly to the cutting of these products into selectedlengths, while reducing the adherence of slag on cut edges of theproducts.

BACKGROUND OF THE INVENTION

[0002] In a continuous casting operation, a continuous cast strand iscut into lengths, such as steel billets, using an oxygen-fuel cuttingtorch system. Oxygen-fuel cutting torch systems are well known and arecommonly used in the cutting and welding industry. A cutting torch ismounted to move with the cast steel strand and to make a lateralseparating cut through the strand perpendicular to its longitudinal axisand its direction of movement.

[0003] Conventionally, the cutting torch is positioned above and moveslongitudinally together with the steel strand while being driven in astraight path transverse to the steel strand. Thus, the cutting torchflame projects downwardly and is moved horizontally across the steelstrand, thereby cutting the billet. During the cutting process, thecutting torch flame produces a kerf in the steel strand. Molten steeland iron oxide flow downwardly through the kerf and drop below thebillet for collection and disposal. However, some of the molten steeland iron oxide adhere to the bottom edges of the kerf and form slagbeads that accumulate along those edges. This slag must be removed;otherwise it adversely affects subsequent forming operations performedon the billets, which may cause defects in finished steel products madefrom the billets. For example, the slag beads may adhere to rollersurfaces used for steel plate forming. Since the slag beads are muchharder than the steel billet, the slag beads may form dimples in therolled steel surface, or embed in the surface. However, removing theslag beads from the billet in a secondary operation, such as scarfing,is tedious, time consuming and costly. Therefore, efforts are generallymade to immediately remove the slag accumulation during the cuttingprocess.

[0004] In general, it has been discovered, and is well known thatdirecting a fluid stream at the molten slag as it forms on the edges ofthe kerf tends to blow it away and thereby reduce its adherence. Thefluid stream may comprise air, oxygen, water, mixtures thereof, or othergases or liquids. U.S. Pat. No. 4,336,078, entitled PROCESS ANDAPPARATUS FOR THE SEPARATION OF METALLURGICAL PRODUCTS, issued to Radtkeon Jun. 22, 1982, for example, describes a process and apparatus forseparating metallurgical products such as ingots, slabs or plate-shapedwork pieces using a cutting torch deposed on one side of the product.The cutting torch follows a prescribed cutting line and forms a frontcutting edge on the surface of the product facing the cutting torch, arear cutting edge on the opposite side of the product, and a cuttingjoint therebetween. At least one gaseous jet is directed at the rearcutting edge of the product to blow away molten metal and liquid slagfrom the rear cutting edge during the cutting process, therebypreventing the formation of slag beads at the edges of the cuttingjoint.

[0005] As another example of the slag adherence reduction, U.S. Pat. No.4,923,527, entitled APPARATUS AND METHOD FOR SLAG-FREE CUTTING OFBILLETS AND THE LIKE, issued to Ludwigson on May 8, 1990, describes abillet cutting apparatus of the type, which includes an oxy-fuel cuttingtorch. The apparatus includes a slag removal nozzle operativesimultaneously with the cutting torch to direct a jet of oxygen alongthe lower edge of the billet to remove slag beads tending to formthereon. The oxygen nozzle has a unique opening configuration, whichprovides a thin, flat oxygen stream effective over a substantialdistance, such that the nozzle can be mounted laterally of the billetand outside the hostile and potentially damaging environment created bythe cutting torch and the hot billet. The oxygen nozzle may beconveniently mounted in a fixed position, and in an automated billetcutting apparatus, may be attached directly to one of the billetclamping arms.

[0006] Neither of these methods has achieved wide commercial success,however. Consequently, there is still a need for alternativetechnologies to minimize slag bead adherence during the cutting of steelbillets, and the like.

SUMMARY OF THE INVENTION

[0007] It is therefore an object of the invention to provide a methodand apparatus for cutting steel with a cutting torch, while reducingslag adherence to a cut edge of the steel.

[0008] It is another object of the invention to provide a method andapparatus for cutting steel, which minimizes slag formation by moving acutting torch in an arcuate path to reduce the area where slag canaccumulate on the cut edges.

[0009] In accordance with one aspect of the present invention, a methodis provided for cutting steel with a cutting torch to reduce slagadherence to a cut edge of the steel. The method comprises steps ofcommencing a cut at a first side of the steel, and moving the cuttingtorch in a arcuate path shaped to continuously aim a cutting flame at afixed point located at a bottom of a first side of the steel, andfollowing the arcuate path to keep the cutting flame aimed at the fixedpoint until the steel is cut.

[0010] When the steel has a bottom surface and an angle of the bottomcorner at the first side is not greater than 90°, it is preferable tomove the cutting torch from the first side of the steel to a second sidewhich is opposite the first side, while gradually rotating the cuttingtorch from a first orientation perpendicular to the bottom surface, andalong the arcuate path to a second orientation parallel to the bottomsurface of the steel, so that the cutting flame of the cutting torch iscontinuously aimed at the bottom corner of the first side of the steel.The cutting torch is preferably moved transversely relative to thesteel, while being maintained stationary relative to a longitudinal axisof the steel. In particular, in continuous cast cutting operations, thecutting torch is moved synchronously with the steel in a directionparallel with the longitudinal axis of the steel. Thus, the molten metaland iron oxide, under the influence of the force of the cutting flamejet, flow toward the bottom corner at the first side of the steel as thecutting torch moves along the arcuate path and the cutting flame therebypivots across the steel. Substantially all of the molten metal and ironoxide drop off below the steel, and only a very small amount of slagbead adheres to the bottom corner of the first side of the steel, whichcan generally be ignored in a subsequent forming process.

[0011] In accordance with another aspect of the invention, an apparatusis provided for cutting steel to reduce slag adherence to the steel. Theapparatus comprises a cutting torch and means for moving the cuttingtorch in an arcuate path to ensure that a cutting flame of the cuttingtorch is always aimed at a bottom corner of the steel.

[0012] The means for moving the cutting torch preferably comprises atrack forming the arcuate path for guiding the cutting torch movement, adrive mechanism operatively connected to the cutting torch to move thecutting torch along the track, and a frame to support the track and thedrive mechanism. A linkage system is preferably included in the drivemechanism to convert a rotational movement of a rotating shaft into themovement of the cutting torch along the track.

[0013] In one embodiment of the present invention, a sleeve havinginternal threads is rotatably connected to the cutting torch about anaxis perpendicular to both a plane determined by the track and alongitudinal axis of the sleeve. A drive shaft is provided which has afree end and an end connected by means of a universal joint, to therotating shaft. The drive shaft has external threads that threadinglyengage the sleeve. The drive shaft is pivotable about an axisperpendicular to the plane of the track and extends through theuniversal joint. Thus, when the rotating shaft rotates the drive shaftthrough the universal joint, the sleeve moves along the drive shaft andcauses the cutting torch to move along the track. The drive shaft may berotated by a motor mounted to the frame.

[0014] The frame may be movable along a path parallel to thelongitudinal axis of the steel and include clamping means for releasablyclamping the steel between the frames in a position in which alongitudinal axis of the steel is perpendicular to the plane determinedby the track. Thus the cutting torch is moved together with the steelwhen, for example, the steel is a continuous cast strand exiting acaster.

[0015] In another embodiment of the invention, a rack and a pinion areprovided to replace the motor for converting the movement of the frameinto the rotational movement of the rotating shaft. The rotating shaftin turn rotates the drive shaft through the universal joint, therebycausing the cutting torch to move along the track. The rack is mountedto a stationary support, such as a track for supporting and guiding themovable frame. The pinion is affixed to the rotating shaft and isadapted to rotate together with the rotating shaft, which is rotatablymounted to the frame.

[0016] In accordance with a further embodiment of the invention, adouble acting fluid cylinder and pivoting linkage system serve as thedrive mechanism. The cylinder is pivotally mounted to the frame about anaxis perpendicular to the plane of the track and is also pivotallyconnected to the cutting torch about an axis, which is alsoperpendicular to the plane of the track. Therefore, the cylinder pivotsabout its mounting axis and the cutting torch is urged along the trackwhen the cylinder is operated in either direction.

[0017] The present invention advantageously provides an alternativetechnology for cutting steel with a cutting torch while reducing slagadherence to the cut edge without using a secondary nozzle to inject afluid stream for slag bead removal.

[0018] Other advantages and features of the present invention will bebetter understood with reference to preferred embodiments of the presentinvention described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Having thus generally described the nature of the presentinvention, reference will now be made to the accompanying drawings,showing by way of illustration the preferred embodiments thereof, inwhich:

[0020]FIG. 1 is a front elevational view of a prior art apparatus forcarrying a cutting torch to move with a continuous cast steel strand;

[0021]FIG. 2 is a general schematic illustration of a prior art methodof cutting a still strand;

[0022]FIG. 3 is a front elevational view of a steel cutting apparatusincorporating a preferred embodiment of the invention;

[0023]FIG. 4 is a schematic illustration of a steel cutting method inaccordance with the invention;

[0024]FIG. 5 is a front elevational view of a steel cutting apparatus inaccordance with another embodiment of the present invention; and

[0025]FIG. 6 is a partial front elevational view of a steel cuttingapparatus in accordance with a further embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0026] As shown in FIGS. 1 and 2, a conventional steel billet cuttingapparatus 10 is adapted to mount a cutting torch 12 for movement with anadvancing continuous steel strand 14 (reference numeral 14 hereinafterindicates either a steel strand, billet, bloom or small slab, whicheveris appropriate). The apparatus 10 includes a pair of downwardlydepending frames 16, which are pivotally connected together by a pivotpin 18 that act as a pair of clamp arms. A hydraulic cylinder 20pivotally connects the respective upper ends 22 of the frames 16, inorder to move clamping members 24 of the frames 16 into clampingengagement with vertical sides of the steel strand 14. The apparatus 10is mounted for movement along a stationary guide track (not shown),which extends parallel to the longitudinal axis of the steel strand orbillet 14. When the frames 16 clamp the steel strand 14 between theclamping members 24, the advancing steel strand 14 moves the apparatus10 along the stationary guide track. A cutting torch 12, shown in FIG.2, is movable transversely across the steel strand 14 as indicated byarrow 28 and thereby cuts the strand 14 into billets. The transversemovement of the torch 12 is driven by a drive mechanism (not shown),which is adapted to mount on the frames 16 of the apparatus 10, so thatthe apparatus and the attached cutting torch 12 are maintained in afixed longitudinal position relative to the moving steel strand 14, sothat the cutting torch is moved over the steel strand 14 to sever thebillet.

[0027] As the cutting flame 30 cuts through the strand 14, as shown inFIG. 2, molten steel and iron oxide flow downwardly between the faces 32(only one of which is shown in FIG. 2) of the steel that define a kerfproduced by the cutting flame 30. Some of the molten material adheres toand forms slag beads 34 along the lower cut edges 36.

[0028]FIG. 3 illustrates a steel billet cutting apparatus 40 inaccordance with an embodiment of the invention. Apparatus 40 is mountedto the frame 16 shown in FIG. 1, the parts of which are indicated by thesame reference numerals and are therefore not described. The apparatus40 includes a track 42 forming an arcuate path 44, shown in FIG. 4. Thetrack 42 is mounted at one end thereof by a mounting plate 46 to one ofthe frames 16, adjacent to the lower end 26 of the frame 16 and abovethe strand 14, which is clamped between the frames 16.

[0029] As shown in FIG. 4, the arcuate path 44 formed by the track isgenerally one quarter of a circular path having its center located at afixed point at which a cutting flame of the torch is continuously aimed.In this example, the center of the circular path is located at a rightside, bottom corner 48 of the strand 14. The arcuate path 44 defines aplane perpendicular to a longitudinal axis of the strand 14. The cuttingtorch 12 (FIG. 3) includes a mechanism for guiding the cutting torch 12along the track 42. For example, rollers (not shown) operatively engagethe track 42. Thus, the cutting torch 12 is adapted to move, as shown inFIG. 4, from the right side 50 of the strand 14 to the left side 52,while gradually rotating from a first orientation 54 perpendicular tothe bottom surface 56, to a second orientation 58 parallel to the bottomsurface 56 of the strand 14. As the cutting torch 12 moves in thearcuate path 44, the cutting flame 30 is always aimed at the right side,bottom corner 48 of the strand 14 and the molten material thereby flowstowards the right-side bottom corner 48. The rate of movement of thecutting torch 12 is dependent on a thickness of the steel, thecharacteristics of the cutting torch nozzle, the type of fuel and otherfactors well known in the art. The cutting torch 12 is preferably movedat a predetermined rate required to cut the steel most efficiently.Cutting the steel using this method results in a very small amount ofslag forming on and adhering to the bottom corner 48 of the billet 14,rather than the significant amount that forms along the entire lower cutedge 36, as shown in FIG. 2.

[0030] Other steel products, for example, blooms and small slabs, whichgenerally have rectangular or square cross-sections, can also be cut inthis manner to reduce slag adherence. The apparatus 40 may also be usedto cut steel that has a non-rectangular cross-section. The cut can beeffected by aiming the cutting flame 30 at a fixed point defined by abottom corner of an imaginary square or rectangle drawn around thestill. In certain instances, efficiency may be increased if the lengthof the arcuate path 44 is greater than one quarter of a circular arc, aswill be understood by those skilled in the art. Interchangeable tracks42 having different radiuses are preferably used to cut respective sizesof steel, in order to keep the path traveled by the cutting torch 12 asshort as possible for any given cutting operation.

[0031] The cutting torch. 12 is moved by a drive mechanism operativelyconnected to the cutting torch 12 and preferably mounted to the sameframe 16 to which the track 42 is mounted. In the embodiment shown inFIG. 3, the drive mechanism includes a sleeve 60 having internal threads(not shown) rotatably connected to the cutting torch 12 at an axisindicated by a “+” 62. The axis 62 is positioned perpendicular to boththe plane determined by the track 42 and a threaded axial bore throughthe sleeve 60. The drive mechanism further includes a drive shaft 64having a free end and an end connected by means of a universal joint 66to a rotation-output shaft 68 of a gear box 70. The drive shaft 64 hasexternal threads for threadingly engaging the internal threads in theaxial bore of the sleeve 60, so that rotation of the rotation-outputshaft 68 moves the sleeve 60 along the drive shaft 64. As the sleeve 60is moved along the drive shaft 64, the drive shaft 64 pivots about anaxis 72 that extends through the universal joint 66. Movement of thesleeve 60 urges the cutting torch 12 along the track 42. The gear box 70is coupled to an electric motor 74, which controllably reciprocates thecutting torch 12 along the track 42. The gear box 70 and the electricmotor 74 are mounted to the frame 16 to which the: track 42 is mountedby a mounting plate 76. The drive mechanism and the track 42 do notinterfere with the clamping action of the frames 16 because they aremounted to only one side of the frames 16.

[0032] In operation, the apparatus 40 is moved along the guide track(not shown) to a predetermined start position while the hydrauliccylinder 22 is retracted to maintain the pair of frames 16 in an openposition. A continuous steel strand 14 exiting from a caster (not shown)advances between the open frames 16. When a predetermined length of thesteel strand 14 has advanced beyond a point aligned with the cuttingtorch 12, the hydraulic cylinder 20 is extended to close the pair offrames 16, thereby clamping the steel strand 14 between the two clampingmembers 24. At this stage, the cutting torch 12 is preferably positionedat a top end of the track 42 and is oriented substantially vertically,as shown in FIG. 3. The apparatus 40 moves forward with the continuoussteel strand 14, and the electric motor 74 begins to rotate the driveshaft 64, thereby urging the cutting torch 12 along the track 42 whilethe cutting torch 12 is operated to produce a cutting flame 30, aimed atthe right-side, bottom corner 48 of the steel strand 14 to begin thecutting operation. When the cutting operation is completed, the cuttingtorch 12 has reached the other end of the track 42, where it is orientedin a substantially horizontal position. The hydraulic cylinder 20 isagain retracted to open the frames 16, and the apparatus 40 is movedback to the predetermined start position. Meanwhile, the electric motor74 rotates the drive shaft 64 in the opposite direction, thereby movingthe cutting torch 12 along the track 42 and back to its start positionin preparation for the next cutting operation.

[0033]FIG. 5 illustrates another embodiment of the invention, in which asteel cutting apparatus 80 is similar to the apparatus 40, shown in FIG.3. The parts of the apparatus 80 which are identical to those ofapparatus 40 shown in FIG. 3 are indicated by the same referencenumerals and are not described. A drive mechanism for the apparatus 80includes a double acting fluid cylinder 82, which urges the cuttingtorch 12 along the track 42. The fluid cylinder 82 may be a pneumaticcylinder or a hydraulic cylinder. The cylinder 82 is pivotally connectedto a support structure 84 about an axis 86 perpendicular to the planedetermined by the track 42. The support structure 84 has a first legmounted to a lower portion of the frame 16 and a second leg mounted toan upper portion of the same frame 16, for example, by a mounting plate88. A ram of the cylinder 82 is pivotally mounted to the cutting torch12 about an axis 90, which is perpendicular to the plane determined bytrack 42. When the cylinder 82 is operated to extend the ram, thecutting torch 12 is urged from the start position at the top end of thetrack 42, as shown in FIG. 5, to move along the track 42 to the endposition, where it is disposed in a substantially horizontally, asdescribed above. When the cylinder 82 is operated to retract the ram,the cutting torch 12 is moved back to the start position.

[0034] Another embodiment of the invention is schematically illustratedin FIG. 6, in which a steel cutting apparatus 100 is similar to theapparatus 40 shown in FIG. 3. The parts of the apparatus 100 which areidentical to those of apparatus 40 shown in FIG. 3 are indicated by thesame reference numerals and are not described. Some of the parts of theapparatus 10 shown in FIG. 1 are omitted from FIG. 6 in order to moreclearly illustrate the differences between the apparatus 100 andapparatus 40. The drive mechanism of the apparatus 100 converts movementof the frames 16 along the guide track (not shown) into rotationalmovement of a rotating shaft 102, which is rotatably supported, forexample, by one or more pillow blocks 104, on the frame 16 to which thetrack 42 is mounted. The rotating shaft is operatively connected to thedrive shaft 64 by the universal joint 66. The gear box 70 (FIG. 3) mayalso be included in the drive mechanism. A pinion 106 is affixed to therotating shaft 102 and is adapted to rotate together therewith. A rack108 is mounted to a stationary support, which, for example, may be theguide track for the movement of the apparatus 10. The pinion 106 engagesthe rack 108 and rolls along the rack 108 as the apparatus 10 is movedalong its guide track. The rotational movement of the pinion 106, whichdrives the rotating shaft 102, rotates the drive shaft 64, so that thesleeve 60 is urged along the drive shaft 64, causing the cutting torch12 to move along the track 42. As will be understood by those skilled inthe art, a mounting linkage (not shown) may be required to keep thepinion 106 in engagement with the rack 108 when the frame 16 is releasedfrom the continuous strand 14 and returned to the start position. Themounting linkage may be incorporated into mounts for the rotating shaft102 or the rack 108, or both.

[0035] As described above, after the cut is completed using theapparatus 100, the hydraulic cylinder 20 is retracted to release theclamping members 24 and the frame 16 is moved back to the startingposition to begin another cut. As the frame 16 is moved back to thestarting position, the linkage mechanism (not shown) keeps the pinion106 engaged with the rack 108 and rotation of the rotating shaft 102returns the torch 12 to the start position at the top of the guide track42.

[0036] Modifications and improvements to the above-described embodimentsof the invention may become apparent to those skilled in the art. Forexample, although the apparatus has been described with reference to thecutting of continuous cast strands, the apparatus described withreference to FIGS. 3 and 5 may likewise be used to cut stationary steelbillets, slabs or beams. For stationary cutting applications, theapparatus 40,80 may be mounted to a stationary base and the steel to becut may be moved into position under the guide track 42 using any one ofmany known heavy material manipulation mechanism. Alternatively, theapparatus 40,80 may be mounted to a mobile base that is rolled or driveninto position over steel to be cut.

[0037] The foregoing description is therefore intended to be exemplaryrather than limiting. The scope of the invention is therefore intendedto be limited solely by the scope of the appended claims.

1. A method of cutting steel with a cutting torch to reduce slagadherence to a cut edge of the steel, comprising steps of: commencing acut at a first side of the steel; moving the cutting torch in an arcuatepath shaped to continuously aim a cutting flame of the cutting torch ata fixed point located at a bottom of the first side of the steel; andfollowing the arcuate path to keep the cutting flame aimed at the fixedpoint until the steel is cut.
 2. A method as claimed in claim 1 furthercomprising steps of moving the cutting torch transversely relative tothe steel, while maintaining the cutting torch stationary relative to alongitudinal axis of the steel.
 3. A method as claimed in claim 1further comprising steps of synchronously moving the cutting torch andthe steel in a direction parallel with a longitudinal axis of the steel,while moving the cutting torch transversely relative to the steel alongthe arcuate path.
 4. A method as claimed in claim 1 further comprising astep of returning the cutting torch to a starting position after thesteel is cut.
 5. An apparatus for cutting steel to reduce slag adherenceto the steel, comprising a cutting torch and means for moving thecutting torch in an arcuate path to ensure that a cutting flame of thecutting torch is continuously aimed at a fixed point at a bottom of oneside of the steel.
 6. An apparatus as claimed in claim 5 wherein themeans for moving comprises a track forming the arcuate path for guidingthe cutting torch movement and a drive mechanism operatively connectedto the cutting torch to move the cutting torch along the track. 7.Apparatus as claimed in claim 6 further comprising a frame forsupporting the track and the drive mechanism.
 8. An apparatus as claimedin claim 6 wherein the drive mechanism comprises a linkage system forconverting a rotational movement of a rotating shaft into the movementof the cutting torch along the track.
 9. An apparatus as claimed inclaim 8 wherein the linkage system comprises: a sleeve having aninternally threaded axial bore connected to the cutting torch androtatable about an axis perpendicular to both a plane determined by thetrack and the internally threaded axial bore; a drive shaft having afree end and an end connected by a universal joint to the rotatingshaft, the drive shaft including external threads for threadinglyengaging the internally threaded axial bore through the sleeve, so thatwhen the rotating shaft rotates the drive shaft, the sleeve is urgedalong the drive shaft and the drive shaft pivots about an axis thatextends through the universal joint, thereby causing the cutting torchto move along the track.
 10. An apparatus as claimed in claim 9 whereinthe rotating shaft is rotated by a motor mounted to the frame.
 11. Anapparatus as claimed in claim 10 wherein the drive mechanism furthercomprises a gearbox connected between the motor and the rotating shaft.12. An apparatus as claimed in claim 6 wherein the drive mechanismcomprises a fluid cylinder pivotally mounted to the frame about an axisperpendicular to a plane determined by the track, the fluid cylinderbeing pivotally connected to the cutting torch so that when the fluidcylinder is operated, the fluid cylinder urges the cutting torch alongthe track.
 13. An apparatus as claimed in claim 12 wherein the fluidcylinder is a pneumatic cylinder.
 14. An apparatus as claimed in claim12 wherein the fluid cylinder is a hydraulic cylinder.
 15. An apparatusas claimed in claim 8 wherein the frame comprises means for releasablygripping the steel with the frame, in a position such that alongitudinal axis of the steel is perpendicular to the plane determinedby the track.
 16. An apparatus as claimed in claim 15 wherein the frameis movable along a path parallel to the longitudinal axis of the steel.17. An apparatus as claimed in claim 13 wherein the drive mechanismcomprises: a rack and a pinion for converting the movement of the frameinto the rotational movement of the rotating shaft, the rack beingmounted to a stationary support and the pinion being affixed to therotating shaft, which is rotatably mounted to the frame.
 18. A method ofcutting steel billets from a continuous cast steel stand to reduce slagadherence to a cut edge of the billets, comprising steps of: commencinga cut at a first side of the steel strand; moving the cutting torch inan arcuate path shaped to continuously aim a cutting flame of thecutting torch at a bottom corner of the first side of the steel strand;and following the arcuate path to keep the cutting flame aimed at thebottom corner until the steel strand is cut to form the steel billet.19. An apparatus for cutting a steel billet from a continuous cast steelstrand to reduce slag adherence to cut edges of the steel billet,comprising a cutting torch and means for moving the cutting torch in anarcuate path to ensure that a cutting flame of the cutting torch iscontinuously aimed at a bottom corner of one side of the steel stranduntil the steel billet is cut from the steel strand.
 20. An apparatus asclaimed in claim 19 wherein the means for moving the cutting torchcomprises: an arcuate track for supporting the cutting torch; and meansfor moving the cutting torch along the arcuate track at a predeterminedrate required to cut the steel strand to form the steel billet.